CAT5 nightmares

[viper0775.livejournal.com]

I'm not sure if this is the right place to post this, but here goes!
My job requries that I modify existing computer systems and segment them off onto their own sub network for the purpose of establishing a VPN tunnel and protecting our equipmet from the rest of the customer network.
First I take the existing 8 port 10/100 switch that is plugged into the customer network and plug it into the LAN port on my VPN/firewall appliance, then I plug the WAN port into the wall, where that hub used to be plugged in.  The rest of the steps are unimportant, the problems I had at the site on Wednesday and Thursday of this week are what have me (and all of my associates) baffled.  I did three out of five projects at this location with no problems, until....

The first happened on Wednesday, I did the above steps and the WAN link light would blink slowly. Standard operation is a solid link light and a flashing activity light.
I first suspected a bad cable, so I swapped it out. then I suspected a bad port on the router, so I tried the LAN port (just for grins) and it showed the same problem. I plugged the original wire back into the wall and it worked fine, so I thought perhaps I had a crossover vs straight through issue, I tried various combinations to no avail. Finally as a last attempt I used a spare network cable that the customer had laying around, a heavy duty shielded cable, and BOOM solid link light. 
   *** A ***   What wiring mistake would require that a shielded/grounded CAT5 cable be used to go from the wall to a network device???

The second problem occurred today (actually they both happened yesterday but I didn't feel like troubleshooting this one then so I got some sleep and came back to it today)
I did the same thing in a different room, pulled the original wire out and plugged my appliance in, this time NO link light at all! This, I thoguht for sure, was a crossover issue, so I swapped out the straight through in favor of a crossover, no luck. so I tried another new of each cable, still nothing. Here is where it gets interesting,
* I plugged a Dell PC into the wall and it worked. 
* I plugged the original swithc, using my cables, into the wall and it worked. 
* I plugged a NEW switch into the wall using my cables, and it worked.
* I plugged my appliance into the wall using the EXISTING cable and it did NOT work.
* I plugged my appliance into the switch and it worked (using any cable I tried)
* I plugged my appliance into the wall using a shielded cable and it did NOT work

NOTHING that I could do would let me use my appliance in THAT wall jack, other jacks worked fine and my spare appliance showed the same symptoms.  I had the customer show me the switch port in his equipment room that was patched over and my appliance linked up fine with the switch directly.  My conclusion is that something was wrong with the way that port was punched down or patched over, but I can't figure out why EVERY other device that I tried would work, except my appliance.

Oh and all devices were set to auto-sense and all are capable of reaching the same speeds.  My solution was to use a different jack in the room.

Comments

[megpie71.livejournal.com]

You're right. This *isn't* the right place to post it.

HTH, HAND, DLTDHYOTAAYGO.

[xanthrant.livejournal.com]

second to this....

this is NOT a support forum....this is a forum for release of frustration of ...people...whom we support. Sorry your delema is shit, but yeah wrong space d00d.

[ozdeadmeat.livejournal.com]

sounds like the patch in the wall is a cross over to me and the appliance doesnt have autosensing of crossover on the nic.

See if the pairs are swapped on the wall socket with a cable tester.

[viper0775.livejournal.com]

oh I should add that I am done at the site and never plan to return. but I did try an un-crossover dongle that I have as well, to no avail.. and the Dell PC NIC wouldn't have linked if it were crossed over (at least I don't expect that it would have)

[ozdeadmeat.livejournal.com]

might be an idea to give it a shot when u have a chance. Most gigabit nics have cross over auto sensing on the cards these days. Might be worth a shot asking the appliance maker and see if there are any flash updates etc. sounds abit odd that it doesnt work through the wall but it does through a switch. Only other thing is that the signal from the appliance is so weak that it doesnt travel more than acouple of feet. But the crossover thing imo is probably what the problem is.

[viper0775.livejournal.com]

That is an idea I've been beggeing for actually =) either autosensing, or a software switch, or a physical switch.. and the device is custom manufactured for my company, we're just asking for too much in the next release, they want to push some stuff back for a future build so they don't change too many things at once. IMHO we could do what we do with a simple linksys and some sveasoft firmware, but what do I know? I'm just the IT Security Specialist.. overpaid and underworked.. *shrug*

[ozdeadmeat.livejournal.com]

yeah well. some people just dont like it when plebs like us come up with ideas that make them look inferior.

Good luck anyway dude.

[viper0775.livejournal.com]

but I'm so damn good at it ;-)

[jahbulon.livejournal.com]

I'd look for the flange receptacle and combrillate it with a bessel.

[zig-mover.livejournal.com]

That's what I usually do when this happens.

[hiroe.livejournal.com]

And when all else fails, Kill It With Fire.

[jecook]

You might have a crosstalk issue if both sides are punched correctly. if you have a fancy tester that does that sort of testing, I'd slam it on there to see what happens.

We have a few drops that won't certify as Cat 6 correctly due to what the tester states is excessive crosstalk. the fact that it's 5e cable is a different one entirely... :) the problem is that the jacks are located in a bar, and tend to get crap splashed all over them, like Cola syrup from the gun that the tenders use.

[tothwolf.livejournal.com]

the problem is that the jacks are located in a bar, and tend to get crap splashed all over them, like Cola syrup from the gun that the tenders use

Hey...I have a solution for that, drop me an email and I'll hook you up :)

[ismarc.livejournal.com]

From the symptoms you are describing I'd almost bet money that you've got a poorly punched/fouled jack or bad cable in the wall. Either way, I think you'd have to tear it out of the wall to fix it.

I'd be willing to bet that the original physical infrastructure was done by a lowest-bid contractor who used mixed category and/or cheap cable. I've seen this (and worked for contractors who've done this) before.

In other words I'm agreeing with jecook.

Of course, I have to wonder what is at the other end of those troublesome jacks, possibly an undocumented switch/hub somewhere? And does your appliance talk on all four pairs?

[jecook]

Ugh. the last place I worked for had their electrictions run the overhead cable. they had the labor for that "donated", along with the cable.

When I got there to term the ends, a) the overhead running was not finished yet; b) the cable was from 2 or 4 different companies and in several different colors (I can dig two, but five? WTF!), and the overhead was not finished to code.

I spent a week in that wretched place trying to get my end done before they sent me home and hired our normal cabling vendor to finish. (who proceeded to bitch about the crap job they had just been handed, and probably will end up tearing it all out and re-running it.) I was NOT pleased, because one of my conditions for even considering doing it was that I get help, and I got none.

Plus the bastards screwed me over for unemployment too, but that's another story. (preferably told over booze)

[tothwolf.livejournal.com]

I still have nightmares when I think about those pics ;)

I can't believe they got away without proper cable supports...

[manuka.livejournal.com]

This is why I always carry a punch tool and a screwdriver with me when I need to go plug something in. Inevitably, something is wired wrong, because some idiot didn't check his work.

I'm a stickler for quality in my cable plant. I spent 3 years on hiatus from IT being a cable monkey, and was fortunate enough to work for a company that valued craftsmanship highly.

[tothwolf.livejournal.com]

My first guess would be a split pair. You can sometimes get away with split pairs on a short run or even 50ft or so at 10mb, but when you get it up to 100mb, it'll act really, really weird.

Even under the best circumstances, there are always one or two jacks that get wired badly in a large install. A lot of the guys who do trimout only test with a one-to-one tester, and those won't detect this type of problem. If you do much in the way of troubleshooting, consider investing in a used Micro Scanner or similar wiremap tester. They are fairly inexpensive used and will show these types of wiring errors. The simple one-to-one 4-led based testers won't detect this sort of problem because they just test for proper continuity.

[ravenshrinkery.livejournal.com]

Pssst. For future reference... techsupport_ot.

Normally the advice that this crowd gives to people asking for serious help is suspect, but they're being nice to you this time. Probably because somebody seriously fucked up and it wasn't your fault :). We've all been there.

[astawater.livejournal.com]

RANTS :p